10,023 research outputs found
Quantum and Classical Chaos in Kicked Coupled Jaynes-Cummings Cavities
We consider two Jaynes-Cummings cavities coupled periodically with a photon
hopping term. The semi-classical phase space is chaotic, with regions of
stability over some ranges of the parameters. The quantum case exhibits dynamic
localization and dynamic tunneling between classically forbidden regions. We
explore the correspondence between the classical and quantum phase space and
propose a scheme for implementing the system experimentally
Fractional Quantum Hall Physics in Jaynes-Cummings-Hubbard Lattices
Jaynes-Cummings-Hubbard arrays provide unique opportunities for quantum
emulation as they exhibit convenient state preparation and measurement, and
in-situ tuning of parameters. We show how to realise strongly correlated states
of light in Jaynes-Cummings-Hubbard arrays under the introduction of an
effective magnetic field. The effective field is realised by dynamic tuning of
the cavity resonances. We demonstrate the existence of Fractional Quantum Hall
states by com- puting topological invariants, phase transitions between
topologically distinct states, and Laughlin wavefunction overlap.Comment: 5 pages, 3 figure
Construction and enlargement of traversable wormholes from Schwarzschild black holes
Analytic solutions are presented which describe the construction of a
traversable wormhole from a Schwarzschild black hole, and the enlargement of
such a wormhole, in Einstein gravity. The matter model is pure radiation which
may have negative energy density (phantom or ghost radiation) and the
idealization of impulsive radiation (infinitesimally thin null shells) is
employed.Comment: 22 pages, 7 figure
The Magnetization of Cu_2(C_5H_{12}N_2)_2Cl_4 : A Heisenberg Spin Ladder System
We study the magnetization of a Heisenberg spin ladder using exact
diagonalization techniques, finding three distinct magnetic phases. We consider
the results in relation to the experimental behaviour of the new copper
compound Cu_2(C_5H_{12}N_2)_2Cl_4 and deduce that the compound is well
described by such a model with a ratio of `chain' to `rung' bond strengths
(J/J^\prime) of the order of 0.2, consistent with results from the magnetic
susceptibility. The effects of temperature, spin impurities and additional
diagonal bonds are presented and we give evidence that these diagonal bonds are
indeed of a ferromagnetic nature.Comment: Latex file (4 pages), related figures (encapsulated postscript)
appende
Quantum phases and topological properties of interacting fermions in one-dimensional superlattices
The realization of artificial gauge fields in ultracold atomic gases has
opened up a path towards experimental studies of topological insulators and, as
an ultimate goal, topological quantum matter in many-body systems. As an
alternative to the direct implementation of two-dimensional lattice
Hamiltonians that host the quantum Hall effect and its variants, topological
charge-pumping experiments provide an additional avenue towards studying
many-body systems. Here, we consider an interacting two-component gas of
fermions realizing a family of one-dimensional superlattice Hamiltonians with
onsite interactions and a unit cell of three sites, whose groundstates would be
visited in an appropriately defined charge pump. First, we investigate the
grandcanonical quantum phase diagram of individual Hamiltonians, focusing on
insulating phases. For a certain commensurate filling, there is a sequence of
phase transitions from a band insulator to other insulating phases (related to
the physics of ionic Hubbard models) for some members of the manifold of
Hamiltonians. Second, we compute the Chern numbers for the whole manifold in a
many-body formulation and show that, related to the aforementioned quantum
phase transitions, a topological transition results in a change of the value
and sign of the Chern number. We provide both an intuitive and conceptual
explanation and argue that these properties could be observed in quantum-gas
experiments
Supersolid phases of light in extended Jaynes-Cummings-Hubbard systems
Jaynes-Cummings-Hubbard lattices provide unique properties for the study of
correlated phases as they exhibit convenient state preparation and measurement,
as well as "in situ" tuning of parameters. We show how to realize charge
density and supersolid phases in Jaynes-Cummings-Hubbard lattices in the
presence of long-range interactions. The long-range interactions are realized
by the consideration of Rydberg states in coupled atom-cavity systems and the
introduction of additional capacitive couplings in quantum-electrodynamics
circuits. We demonstrate the emergence of supersolid and checkerboard solid
phases, for calculations which take into account nearest neighbour couplings,
through a mean-field decoupling.Comment: 9 pages with 6 figures, accepted for publication in Physical Review
Recommended from our members
Complex Coacervation of Polymerized Ionic Liquids in Non-acqueous Solvents
Oppositely charged polymerized ionic liquids (PILs) were used to form complex coacervates in two different organic solvents, 2,2,2-trifluoroethanol (TFE) and hexafluoro-2-propanol (HFIP), and the corresponding phase diagrams were constructed using UV–vis, NMR, and turbidity experiments. While previous studies on complex coacervates have focused almost exclusively on aqueous environments, the use of PILs in the current work enabled studies in solvents with substantially lower dielectric constants (27.0 for TFE, 16.7 for HFIP). The critical salt concentration required to induce complete miscibility was roughly 2-fold larger in HFIP compared with TFE, and two different PIL complexes, solidlike precipitates and liquidlike coacervates, were found in both systems. This study provides insight into the effects of low-dielectric-constant solvents on complex coacervation, which has not been widely studied because of the limited solubility of conventional polyelectrolytes in these media
- …